Differential Diagnosis for Unilateral Foot Drop
- Single most likely diagnosis
- Peroneal nerve palsy: This is the most common cause of unilateral foot drop, often resulting from compression or trauma to the peroneal nerve, which can occur at various sites including the knee or fibular head.
- Other Likely diagnoses
- L5 radiculopathy: Compression or damage to the L5 nerve root can cause foot drop due to the nerve's involvement in controlling the muscles responsible for ankle dorsiflexion.
- Stroke or cerebral vasculature issues: Although less common than peripheral causes, unilateral foot drop can be a manifestation of a stroke or other cerebral vascular events affecting the motor areas of the brain responsible for lower limb control.
- Muscular dystrophy: Certain types of muscular dystrophy, such as Duchenne muscular dystrophy, can lead to foot drop among other muscle weaknesses.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
- Cauda equina syndrome: A serious condition that requires urgent medical attention, cauda equina syndrome involves compression of the nerve roots in the lower spine and can present with foot drop among other symptoms like bladder and bowel dysfunction.
- Spinal cord compression: Compression of the spinal cord, which can be due to various reasons including tumors, abscesses, or fractures, is a medical emergency that can cause foot drop if the compression involves the areas of the spinal cord controlling lower limb function.
- Diabetic amyotrophy: A complication of diabetes, diabetic amyotrophy can cause significant pain, muscle weakness, and wasting, including foot drop, and requires prompt management to prevent further deterioration.
- Rare diagnoses
- Charcot-Marie-Tooth disease: A group of inherited disorders that affect the peripheral nerves, leading to progressive muscle weakness and atrophy, including foot drop.
- Poliomyelitis: Although rare in areas with widespread vaccination, polio can cause foot drop among other neurological deficits.
- Neurosyphilis: A complication of untreated syphilis, neurosyphilis can lead to a variety of neurological symptoms, including foot drop, though this is exceedingly rare in the modern era with availability of effective treatments for syphilis.